What are the Jewels in the Context of Watch Movements ?

The jewels are synthetic sapphires or rubies which have been drilled, chamfered and polished to serve as bearings for gears in watches, reducing friction or mechanical parts to a bare minimum.

Generally speaking, on may say that a simple mechanical watch (hours, minutes and seconds hands) should include at least fifteen jewels located in the places most subject to wear due to friction. It should be fitted with a shock-absorbing system on the balance, a good quality balance-spring and an unbreakable spring.